Electric Transport Properties Of Graphene-boron Nitride Heterojunction FET And Cr₂C

Due to the breakdown of diode,its application into real life remains challenging.With the development of technology,the age of transistors is coming into sight.Field effect transistors(FET),making outstanding contributions to the development of science and technology,take an increasingly important role in integrated circuit(IC).Metal-oxide semiconductor FET are able to achieve diode-effect,easily to be integrated and without secondary breakdown,which produce a marked effect in IC.According to the limit of Moore's law,the pursuit of new materials to design FET has been a research focus in various fields.Graphene with prominent quality,discloses the door of two-dimension(2D)materials and draw the attention of researchers.FET formed by graphene has spurred a surge in the study of spintronic devices.But,lacking of bandgap lead to a limit of its practical utility.However,h-BN can open the energy band of graphene,promoting the investigation of graphene and BN heterojunction.The study about graphene and BN heterojunction in diode transportability is rare.Therefore,the first work of the thesis is to investigate the electrical properties of graphene BN heterostructure FET under single gate and double gates based on extending Huckel's theory.The result implies that there is an excellent bidirectional diode effect under the single gate(under the regulation of gate voltage,there is current flow in both the positive and negative directions of the heterojunction),and the switch ratio can reach 10⁴.It is found that the electrical properties of the heterojunction under double gate are the same as that of the single gate in the range of-2V?2V.When the gate voltage exceeds this range,the properties become different.So we can make different types of gate of graphene boron nitride heterostructure FET according to the actual demand.The two-dimensional material graphene induce magnetism by doping.While the concentration of doping in the experiment is difficult to be controled.Searching for 2D materials with magnetic and easy to be synthesized is very necessary to the development of spintronics.The transition-metal carbide is a new 2D material.Thus,the second work of this thesis is to investigate the fundamental properties of transition-metal carbons X₂C(X=Sc?Ti?V?Cr?Mn?Fe?Co?Ni?Cu?Zn)based on density function theory(DFT).The results show that Cr₂C has half-metal properties.The electrical transport properties of spintronic devices of Cr₂C are simulated.The results demonstrate that the maximum value of spin polarization can reach 97.44%.